The present invention relates to a cylinder apparatus which can be used as, for example, a pump, a compressor or a fluid motor, and more particularly to a rotary cylinder apparatus in which a piston moves into or from a cylinder chamber by the rotary motion.
A term xe2x80x9crotary cylinder apparatusxe2x80x9d used in this specification includes a device which performs a mechanical task by using fluid energy as well as a device which compresses and thrusts a fluid by using rotational energy. That is, the term xe2x80x9crotary cylinder apparatusxe2x80x9d means devices that generically designate a rotary pump, a rotary compressor, a fluid motor and others.
As a pump which is of a type for rotating a rotor and thrusting a fluid by a displacement effect, there is known a rotary pump using a gear type rotor. In case of this pump, however, the tooth profile of the rotor is hard to be machined, which results in increase of the cost. Thus, in order to eliminate this problem, the present applicant has developed a rotary cylinder apparatus having a structure in which an intake and discharge mechanism does not require a gear component (see Japanese Patent Application Laid-open No. 118501/1981, Japanese Utility Model Application Laid-open No. 87184/1982, and Japanese Utility Model Application No. 92486/1983).
The rotary cylinder apparatus disclosed in Japanese Patent Application Laid-open No. 118501/1981 has, as shown in FIGS. 67 and 68, a circular cylinder member 102 fixed to the inside of a casing 101 by press fitting and the like, and a support member 104 which rotates in a circular hollow portion 103 formed at a central part of this cylinder member 102. To the cylinder portion 102 are formed six cylinder chambers 105a, 105b, 105c, 105d, 105e and 105f which are radially arranged and respectively communicate with the central hollow portion 103. The respective cylinders 105a to 105f are provided so as to sequentially communicate with a suction opening 106 which communicates with the outside of the casing 101 to take a fluid into the cylinder apparatus and a discharge opening 107 which applies a pressure to the taken fluid to discharge it, as the support member 104 rotates.
The support member 104 is a discoid member fixed to one end of a shaft 108 rotatably supported by a hole 101a formed to the casing 101, and a lunate valve sheet 109 is attached on a surface opposite to the shaft 108. This valve sheet 109 is arranged so as to be capable of rotating in the appressed manner in an area corresponding to substantially the semicircle of an inner wall portion 103a of the cylinder member 102 and provided so as to cause the hollow portion 103 to selectively communicate with an arbitrary cylinder chamber. It is to be noted that a hole 104a for communicating with the discharge opening 107 is provided to the support member 104.
A shaft 110 is fixed at an eccentric position of the support member 104, and a rotary piston member 111 is rotatably supported by this shaft 110. Both ends of the shaft 110 are fixed to the discoid support member 104 and an auxiliary plate member 113 which are arranged so as to be opposed to each other with the valve sheet 109 therebetween. A hole 113a for communicating with the suction opening 106 is provided to the auxiliary plate member 113. This auxiliary plate member 113 integrally rotates with the support member 104. The rotary piston member 111 is constituted by a rotation center portion 112a and pistons 111a, 111b and 111c radially extending in three directions from the rotation center portion 112a. The rotary piston member 111 moves around a shaft center o1 of the cylinder member 102 as the support member 104 rotates.
As shown in FIGS. 68A to 68D, when the respective pistons 111a, 111b and 111c rotate (revolution) around shaft center o1 in a direction indicated by an arrow B1 while rotating (autorotation) around the shaft 110 in a direction indicated by an arrow A1 as the support member 104 rotates, the three pistons 111a to 111c sequentially move into or from the respective fixed cylinder chambers 105a to 105f so that the outside air is sequentially taken from the suction opening 106 into the respective cylinder chambers 105a to 105f and discharged from the discharge opening 107 to the outside. This pump operation is repeated. According to this apparatus, since the advanced tooth profile finishing technique is not required, manufacture is facilitated.
However, since the respective pistons 111a to 111c move into or from the cylinder chambers 105a to 105f while rolling, they must have a structure that their end portions are sharpened and the dimension of each of the pistons in the widthwise direction has a margin when they enter the cylinder chambers 106a to 105f in order to smooth and facilitate the operation of each piston. Accordingly, a gap is thereby formed between the pistons 111a to 111c and the cylinder chambers 105a to 105f. As a result, a fluid tends to flow from the gap portion, and the pump efficiency is thereby disadvantageously lowered.
Further, the rotary cylinder apparatus disclosed in Japanese Utility Model Application Laid-open No. 87184/1982 and Japanese Utility Model Application Laid-open No. 92486/1983 is the same as the counterpart disclosed in Japanese Patent Application Laid-open No. 118501/1981 mentioned above in the basic structure, namely, that the radially arranged pistons relatively rotationally move along the radially arranged cylinder chambers while rotating to obtain the pump effect. However, this rotary cylinder apparatus is different from the former apparatus in that the cylinder member 102 rotates by rotation of the rotary piston member 111, the valve sheet 109 is fixed to the case and does not rotate, and a rotation supporting point of the rotary piston member 111 does not swivel.
In case of the type that the cylinder chamber rotates together with the rotary piston member, therefore, the piston is formed into a substantially circular disc shape whose outer diameter is nearly equal to a width of the cylinder chamber, as different from the above-described type that the cylinder chamber is fixed. That is because the smooth operation is enabled even if there is substantially no gap between the pistons and the cylinder chambers when the pistons move into or from the cylinder chambers since the cylinder member also rotates in the same direction as the rotary piston member. However, in case of this type, since the contact surface between the piston and the cylinder chamber is constituted by an outer peripheral surface of the circular disc-like piston and the inner wall of the linear cylinder chamber, an area of this contact surface is so small that this part can not withstand a pressure of a fluid. Consequently, the fluid leaks, and the pump effect lowers when the pressure is increased.
It is an object of the present invention to provide a rotary cylinder apparatus which can prevent a fluid from leaking from the contact portion between the piston and the cylinder member and thereby convert the fluid energy into the rotary motion or the rotary motion into the fluid energy with small losses.
To achieve this aim, according to the present invention, there is provided a rotary cylinder apparatus comprising: a rotary cylinder member which has a cylinder chamber formed thereto so as to pass through a rotary shaft center and rotates around the rotary shaft center; a piston which demonstrates the reciprocating linear motion in surface contact with the inside of the cylinder chamber; a piston holding member which supports the piston and rotates around a rotation center eccentric from the rotary shaft center of the rotary cylinder member; and a casing which rotatably supports the rotary cylinder member and the piston holding member and has at least one fluid inlet and at least one fluid outlet, wherein the piston is held at a position away from the rotation center of the piston holding member by a fixed distance and held so as to be capable of swiveling around that position.
Therefore, when rotation is inputted to the rotary cylinder portion or the piston holding member from the outside, or when a fluid having a pressure is led from the fluid inlet so that the pressure acts on the piston in the cylinder chamber, the piston rotates (revolution) around the rotation center of the piston holding member while rotating around the center of autorotation by rotation of the rotary cylinder member and the piston holding member or movement of the piston itself, thereby causing the reciprocating motion of the piston in the cylinder chamber.
At this moment, the rotary cylinder member and the piston holding member can rotate while being respectively supported by the casing, and the piston can also rotate by itself. Thus, the piston can perform the linear motion in the cylinder chamber while rotating around the autorotation center and changing its position. As a result, even if the piston is configured to be in surface contact with the cylinder chamber, each member can demonstrate the smooth rotary motion. For example, even if the piston has a block-like shape, each member can smoothly perform the rotary motion. As a result, the piston can be readily manufactured, thereby facilitating improvement in the accuracy of the piston. Here, it is preferable to configure the apparatus in such a manner that a ratio of the rotation number of the rotary cylinder member, the rotation number of the piston holding member and the number of times of reciprocation of the piston in the cylinder becomes 1:2:1. In this case, the respective members can assuredly rotate without any trouble, and vibrations or noises during the rotation can be reduced.
Moreover, a contact area between the piston and the cylinder chamber can be enlarged, and the fluid resistance in the contact surface is large as compared with a prior art in which the contact surface is formed by so-called line contact, thereby preventing the fluid from leaking from the contact surface portion. As a result, it is possible to convert the fluid energy into the rotary motion or the rotary motion into the fluid energy with the small losses.
In addition, since the piston demonstrates the reciprocating linear motion in the cylinder chamber, the piston operation becomes smooth and stable, thereby obtaining the structure by which vibrations or noises during rotation can be reduced. Additionally, the tolerance of the component accuracy can be increased, and the components can be easily fabricated. On the contrary, in case of the component accuracy level which is similar to that in the prior art, the air-tightness/reliability can be improved. Therefore, in case of a pump, a compressor, or a fluid motor, realization of the high performance can be facilitated.
Further, in the rotary cylinder apparatus according to the present invention, when the rotary shaft center of the rotary cylinder member is a drive shaft for leading rotation from the outside, the piston and the piston holding member can be driven and operated by swiveling this rotary cylinder member. By doing so, the rotary cylinder apparatus can be utilized as a compressor for sucking, compressing and discharging gas or a pump for sucking and discharging a liquid. Furthermore, a so-called center drive specification is enabled. When the drive shaft and the motor shaft are directly connected to each other in the coaxial direction, the settlement as a product is good, which is advantageous in terms of vibrations or assembling.
For example, in case of constituting as a rotary compressor, the piston is moved by relatively rotating the rotary cylinder member and the piston holding member by a rotational drive source, and a fluid sucked from the fluid inlet is discharged from the outlet. At this moment, the fluid inlet is formed so as to extend from a position which is slightly closer to the inner side from a position to which the piston has moved on the outmost periphery with rotation of the rotary cylinder member to a position to which the piston has moved in the vicinity of the hollow portion. On the other hand, it is preferable that the outlet is provided at a position which is slightly distanced in the frontward position from a position to which the piston has moved on the outmost periphery with rotation of the rotary cylinder member. Furthermore, it is preferable to provide a check valve to the outlet which is a discharge opening. In this case, since the respective cylinder chambers are sequentially opposed to the outlet as the rotary cylinder member rotates, the fluid can be prevented from flowing backwards when the pressure is lowered due to the action of the check valve even if the pressure of the fluid discharged from the outlet pulsates. Moreover, it is preferable to connect an input shaft for relatively rotating the rotary cylinder member and the piston holding member with the rotary cylinder member or the piston holding member through a carrier plate. In this case, for example, even if the center of the input shaft deviates from the center of the rotary cylinder member when rotation of the input shaft is transmitted to the rotary cylinder member, this deviation can be absorbed between the cylinder member and the carrier plate to transmit the turning force. Similarly, even if the center of the input shaft deviates from the center of the piston holding member when rotation of the input shaft is transmitted to the piston holding member, the carrier plate can absorb this deviation to transmit the turning force.
Further, when the rotary cylinder member and the piston holding member are rotated when the pressure fluid is led into the cylinder chamber to move the piston by using the pressure of the fluid, it is possible to constitute a fluid rotating machine capable of taking out rotation with at least one of the rotary cylinder member and the piston holding member being used as an output shaft. Furthermore, in case of the fluid rotating machine, it is preferable to open the fluid inlet so as to communicate with the cylinder chamber when the piston is at a substantially outer peripheral position of the rotary cylinder member as the rotary cylinder member rotates as seen from the rotary shaft center of the rotary cylinder member and so as to close the cylinder chamber when the piston has passed the substantially central position of the rotary cylinder member, and form the fluid outlet so as to communicate with the cylinder chamber before the piston reaches the substantially central position of the rotary cylinder member as the rotary cylinder member rotates as seen from the rotary shaft center of the rotary cylinder member and so as to close the cylinder chamber at the substantially outer peripheral position of the rotary cylinder member. Incidentally, when constituting the rotary cylinder apparatus as a rotary compressor, it is preferable to form the fluid inlet so as to communicate with the cylinder chamber when the piston reaches the substantially outer peripheral position of the rotary cylinder member as the rotary cylinder member rotates as seen from the rotary shaft center of the rotary cylinder member and so as to close the cylinder chamber at the substantially central position of the rotary cylinder member, and form the fluid outlet so as to communicate with the cylinder chamber when the piston reaches the substantially central position of the rotary cylinder member as the rotary cylinder member rotates as seen from the rotary shaft center of the rotary cylinder member and so as to close the cylinder chamber at the substantially outer peripheral position of the rotary cylinder member.
Moreover, when constituting the rotary cylinder apparatus as such fluid rotating machines, it is preferable that the rotary cylinder apparatus is provided with a lubricant circulation mechanism. In this case, lubrication on sliding surfaces of the piston, the piston holding member, the rotary cylinder member and the like enables the high-speed rotation.
In addition, a fluid electric generator may be constituted by connecting an electric generation mechanism to the output side of the above-described fluid rotating machine. In this case, the above-mentioned fluid rotating machine can be used to generate electricity.
Additionally, in the rotary cylinder apparatus according to the present invention, a guide portion for guiding the piston in the sliding direction is formed to the cylinder chamber, and a guide engagement portion engaging with the guide portion is formed to the piston. Therefore, the reciprocating linear motion of the piston is smoothed when this motion is performed while the guide engagement portion is guided by the guide portion.
Further, in the rotary cylinder apparatus according to the present invention, the fluid inlet is provided to the casing in any one of areas divided by a line connecting the rotary shaft center of the rotary cylinder member and the rotation center of the piston holding member so as to communicate with the cylinder chamber, and the fluid outlet is provided to the casing in the other one of the areas divided by the line connecting the rotary shaft center of the rotary cylinder member and the rotation center of the piston holding member so as to communicate with the cylinder chamber. In this case, the inlet and the outlet can be arranged so as to be sufficiently distanced from each other. Even if a difference between the pressure of the fluid on the inlet side and the pressure of the fluid on the outlet side is large, the fluid can be prevented from directly flowing from the inlet toward the outlet or from the outlet toward the inlet without passing through the cylinder chamber. In particular, it is preferable to provide the inlet and the outlet of the fluid at positions opposed to the outer peripheral surface side of the rotary cylinder member of the casing. By providing them in this manner, each cylinder chamber, the inlet and the outlet can be configured so that each cylinder chamber can communicate with the outer peripheral surface of the rotary cylinder member, which results in the excellent settlement of the product.
Furthermore, in the rotary cylinder apparatus according to the present invention, it is preferable that a surface of the piston opposed to the piston holding member is a flat surface. In this case, the movement of the piston is smoothed with respect to the piston holding member. Moreover, it is possible to prevent a gap from being formed between the piston and the piston holding member, thereby avoiding leakage of the fluid.
In addition, in the rotary cylinder apparatus according to the present invention, it is preferable that the lateral cross-sectional shape of the piston and the lateral cross-sectional shape of the cylinder chamber are like shapes by which a small gap for enabling sliding is formed. In this case, it is possible to prevent a gap from being generated between the rotary cylinder member and the piston, thereby avoiding leakage of the fluid. Here, the shape of the piston does not have to be a special shape as long as it matches with the cross-sectional shape of the cylinder chamber. For example, even if the piston has a block shape such that all the entire surfaces are formed by the flat surfaces, each member can demonstrate the smooth rotary motion. As a result, the piston can be readily manufactured, the high accuracy of the piston can be easily obtained. Additionally, on the side surface of the piston may be provided a flat surface which is in surface contact with at least one of the flat side surfaces of the cylinder chamber, or preferably both of the side surfaces, or most preferably all the four surfaces including the surfaces configured by the piston holding member or the casing. Further, the lateral cross-sectional shape of the piston is not restricted to a rectangular shape and may be a different shape. The lateral cross-sectional shape of the cylinder chamber may be matched with the shape of the piston. In this case, since both of the side surfaces of the cylinder chamber on which the piston slides do not have to be vertically formed with respect to the bottom surface, the cylinder chamber can be readily processed. For example, when both corner portions on the bottom surface of the piston are rounded, the corner portions of the cylinder chamber on which the piston slides can be rounded, thereby further facilitating processing of the cylinder chamber.
Furthermore, in the rotary cylinder chamber according to the present invention, it is preferable to provide on these slide surfaces back pressure releasing means for reducing the back pressure which can be the resistance of the relative rotation of the rotary cylinder member and the piston holding member. In this case, when the piston operates and the rotary cylinder member and the piston holding member rotates, the back pressure which disturbs the movement of these members is generated, but the back pressure releasing means reduces the back pressure, thereby smoothing the movement of the rotary cylinder member and the piston holding member. For example, the back pressure releasing means may be piston back-and-forth movement back pressure releasing means for releasing the back pressure which acts in the moving direction of the piston, or cylinder side back pressure releasing means for releasing the back pressure generated between the rotary cylinder member and the casing, or piston holding member side back pressure releasing means for releasing the back pressure generated between the piston holding member and the casing. Further, all of these means may be provided.
Moreover, in the rotary cylinder apparatus according to the present invention, it is preferable that the rotary cylinder member and the piston holding member are rotatably supported by a bearing member which simultaneously bears the thrust load and the radial load. In this case, the structure of a part rotatably supporting the rotary cylinder member and the piston holding member becomes simple, thereby reducing the size and the cost of the apparatus.
In addition, in the rotary cylinder apparatus according to the present invention, the rotary cylinder member is rotatably supported by a bearing plate and the bearing plate is constituted so as to be adjustable by an adjusting pushing screw and an adjusting drawing screw in some cases. In this case, varying a quantity of screwing of the pushing screw and the drawing screw can adjust the tilt of the bearing plate supporting the rotary cylinder member. Consequently, the component accuracy of the rotary cylinder member in the thrust direction can be mollified.
Further, in the rotary cylinder apparatus according to the present invention, the piston holding member is rotatably supported by the bearing plate and the bearing plate is constituted so as to be adjustable by an adjusting pushing screw and an adjusting drawing screw in some cases. In this case, varying a quantity of screwing of the pushing screw and the drawing screw can adjust the tilt of the bearing plate supporting the piston holding member. As a result, the component accuracy of the piston holding member in the thrust direction can be mollified.
Furthermore, in the rotary cylinder apparatus according to the present invention, a magnetic fluid can be arranged at a gap formed between the piston and the cylinder chamber and a magnet for holding the magnetic fluid at the gap can be provided in the vicinity of a contact part between the piston and the cylinder chamber. In this case, the magnetic fluid held by the magnet is filled in the gap between the piston and the rotary cylinder member. Therefore, the small gap at a part where the piston is opposed to the cylinder member is further assuredly sealed, thereby further securely preventing the fluid from leaking from the contact part.
Moreover, in the rotary cylinder apparatus according to the present invention, a plurality of pistons and a plurality of cylinder chambers are formed, and it is preferable that a plurality of the cylinder chambers are formed so as to pass through and cross the rotary shaft of the rotary cylinder member. In this case, the rotary cylinder apparatus which rotates by a plurality of the pistons is provided.
In addition, in the rotary cylinder apparatus according to the present invention, the cylinder chambers are arranged to the rotary cylinder member at positions equally distributed in the circumferential direction. Therefore, the balance of rotation of the rotary cylinder member is improved, and vibrations or noises can be prevented from occurring, thereby providing the rotary cylinder apparatus suitable for the high-speed rotation.
Additionally, in the rotary cylinder apparatus according to the present invention, a length of a part where a plurality of the cylinder chambers cross each other in the moving direction of the piston is shorter than a length of the piston. Therefore, the piston demonstrating the reciprocating linear motion is guided by the wall surfaces of the cylinder chamber which is moving when the piston passes the part where the cylinder chambers cross each other, and crosses other crossing cylinder chambers. Thus, the piston can smoothly pass without colliding with other cylinder chambers.
Further, in the rotary cylinder apparatus according to the present invention, it is preferable that a chamfer portion is formed at the part where a plurality of the cylinder chambers cross each other. In this case, the piston can further smoothly pass the part where the cylinder chambers cross each other.